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Biomedical subjects

K Schwabe

Publications and source records attributed to K Schwabe.

At least 37 records · Page 2Linked to original sources

Protection of melanoma cells against superoxide radicals by melanins.

Human melanoma cells transplanted into immunocompetent mice by the 6-day subrenal capsule technique are characterized by high resistance against immunological attack. This resistance is suggested to be the consequence of scavenging of superoxide free radicals by melanin. Scavenging of superoxide radicals by the melanoma cells was clearly demonstrated using electron spin resonance techniques. From comparison with synthetic melanins it is concluded that the scavenger effect can be attributed mainly to low-molecular-mass melanins synthesized in the melanoma cells whereas high-molecular-mass melanins are practically ineffective.

Animals↗

[A comparison of the course of anesthesia using a bolus application of propofol, methohexital or etomidate as hypnotics and alfentanil analgesia].

The suitability of the analgesic-hypnotic combination alfentanil-propofol in nitrous oxide-oxygen IPPB for short-term and outpatient anesthesia was studied in 50 patients of ASA risk groups I and II. This study appeared pertinent since the two substances have the shortest half-lives of their respective classes of medication. For comparison, two groups of similar size were treated with the well-established combinations alfentanil-methohexital and alfentanil-etomidate. During the entire intra- and postoperative periods the circulatory parameters were frequently monitored as was the continuous recording of the compressed spectral array in the EEG. Thirty minutes after extubation three modified tests of recovery were carried out that were compared to the preoperative results. For a subjective evaluation, a multiple choice questionnaire was answered by each patient after the recovery tests. The mean duration of anaesthesia in all three groups was 1 h. All three combinations were found to be agreeable to the patients with the best results in the propofol group. These patients also showed the most rapid recovery; consequently, the combination of alfentanil and propofol would appear to be especially suitable for outpatients. For the induction of anesthesia alfentanil was administered in a dosage of 30 micrograms/kg body weight in combination with propofol 1.5 mg/kg, methohexital 1.0 mg/kg or etomidate 0.2 mg/kg. For anesthesia maintenance the following mean dosages were found to be suitable: Alfentanil 1 microgram/kg/min, propofol 46 micrograms/kg/min, methohexital 24 micrograms/kg/min, and etomidate 4 micrograms/kg/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

[Synthesis and melanoma inhibiting properties of 4-alkylpyrocatechol-2-O-beta-D-glucopyranosiduronic acids and their esters].

Using two sources of selection, the higher beta-glucuronidase and tyrosinase content of malignant melanomas, new transport forms are synthetized, which are toxified to quinoids, cytotoxic products by the above mentioned enzymes. These transport forms selectively inhibit the growth of melanomas. For instance, 4-methylcatechol-2-O-beta-D-glucopyranosiduronic acid (3) is synthetized by the reaction of 4-methylcatechol with tetra-O-acetyl-beta-D-glucopyranosiduronic acid methyl ester in the presence of p-toluenesulfonic acid following treatment with alkali. 3 inhibits the growth of B16 melanoma of the mouse significantly.

Animals↗

[Synthesis of 5-bromosalicyl-4'-chloroanilide-O-beta-D-xylopyranoside and other transport forms enzymatically activated by microbes].

The synthesis of 5-bromosalicyl-4'-chloroanilide-O-beta-D-xylopyranoside and other glycosides of 5-bromosalicyl-4'-chloroanilide, salicylanilide, 3,5-dichlorophenol and tetrachlorohydrochinone is described. Glycosidations follow the procedures described by Latham et al. Sabalitschka and Helferich et al. These glycosides represent relatively untoxic transport-forms of drugs, which are activated to the free drug by specific enzymes of the organisms to be destroyed. This new mechanisms can help to destroy fungi and parasites in dermatology, agriculture, horticulture and cultivation of decorative plants without side effects on the host.

Anti-Infective Agents↗

Glycosidation of chlormadinol acetate alters its actions on Na+/K+-transporting ATPase and cardiac contractility: a contribution to the endogenous digitalis problem.

Compared to the progesterone derivative chlormadinol acetate 1, the arabinofuranoside 2, rhamnoside 3 and glucoside 4 of 1 are less potent in the Na/K-ATPase assay, but evoke, contrary to 1, positive inotropy in vivo. In anaesthetized cats the circulation effects of 2 and 3 appear to be more favourable than those of the digitalis glycoside digitoxin. Hence, the progestin 1 is transformed through glycosidation into an interesting cardioactive steroid.

Animals↗

[Methotrexate recovery].

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Chromatography, High Pressure Liquid↗

[Catheter peridural anesthesia with bupivacaine HCI and bupivacaine CO2. A comparison and the effects of premedication].

A controlled prospective randomized study was carried out to compare the action of 0.5% bupivacaine-CO2 and 0.5% bupivacaine-HCI both with and without diazepam premedication. Those patients given an epidural with 0.5% bupivacaine-CO2 and diazepam premedication showed both the briefest time to onset of action and the greatest degree of motor block. In contrast to the other three groups, none of these patients had missed segments. Despite the fact that no significant differences could be calculated, the difference in intensity of action observed in this investigation may well be of clinical relevance.

Aged↗

[Synthesis and properties of digitoxigenin-3 beta-O-alpha-L-arabinofuranoside].

The synthesis of a cardenolide glycoside with a furanoide sugar component, digitoxigenin-3 beta-O-alpha-L-arabinofuranoside (4), is described for the first time. 4 was prepared by the reaction of digitoxigenin with 2,3,5-tri-O-benzoyl-alpha-L-arabinofuranosylchloride and Fétizon-reagent in benzene/dioxan followed by debenzoylation with ammonia in dry methanol. Compound 4 is cleaved by alpha-L-arabinofuranosidase (Aspergillus niger K1) into digitoxigenin and L-arabinose. Hydrolytic stability against methanolic HCl (0.1 mol/l) is relatively high. 4 X 10(-8) mol/l 4 gives a 50% inhibition of the Na,K-ATPase (pig heart muscle) and is 2.5 times more active at this receptor than the aglycon digitoxigenin.

Animals↗

Chemotherapy for tumours using clostridial oncolysis, antibiotics and cyclophosphamide: model trial on the UVT 15264 tumour.

Lysis of the UVT 15264 tumour in mice of the 17/Berlin-Buch strain as induced by intravenous injection of Clostridium butyricum H8 spores is followed by the tumour diameter and survival time. In animals thus treated, tumour regression is incomplete and the mean survival time drops below that of tumour-bearing animals not treated with spores. With concurrent antibiotic treatment survival time is prolonged to exceed that of untreated animals, without affecting ocolysis-provoked tumour regression. When spore is combined with cyclophosphamide, tumour regression is considerably improved, but the survival resembles that of untreated tumour-bearing animals; with both cyclophosphamide and antibiotic treatment survival resembles that of spore-treated animals.

Animals↗

[Yersinioses. Clinical, patho-anatomical and pathogenetic problems (author's transl)].

On the basis of a selected patient group and bioptic material, the difficulties in diagnosing Y. pseudotuberculosis and Y. enterocolitica infections are presented from the clinical and morphological point of view, particularly when extraintestinal complications are present. Taking one patient with Y. enterocolitica infection and recurrent oligoarthritis as an example, the possible pathogenetic significance of circulating immune complexes for the development of extraintestinal symptoms is being discussed.

Adolescent↗

Measurement of specific multiplication of an oncolytic and a nononcolytic strain of Clostridium butyricum inside the tumour UVT 15264 of the mouse.

Clostridium butyricum was recultivated from tumour material after treatment of tumour-bearing mice with spores and counted by soft agar colony technique. The oncolytic strain Cl. butyricum H8 grows inside the tumour UVT 15264 up to 8 X 10(8)/g during 48 h. In this time part of tumour became lysed. Multiplication inside of this tumour by the tumour specific but nononcolytic strain Cl. butyricum CNRZ 528 could not be detected by application counting technique. Combination of spore treatment with antibiotic chemotherapy in dosage able to prevent oncolysis or in dosage to reduce them corresponds with loss of clostridial multiplication or with reduced vegetative multiplication respectively.

Animals↗

Experiments to increase the selectivity of tumor chemotherapy by means of in vivo activation of transport forms of cancerostatics by exogenous enzymes.

A significant tumor damaging effect (growth inhibition) on transplanted syngeneic sarcoma in mouse was obtained by means of pH-dependent activation of a transport form of a cancerostatic drug by an enzyme foreign to the organism. This effect was achieved by combined administration of 8-0-(alpha-L-arabinofuranosyl)beta-peltatin-A as a transport form of beta-peltatin-A and the exogenous enzyme alpha-L-arabinofuranosidase from Aspergillus niger and additional increase of the acidity of the tumor by injection of glucose. The combined application of the transport form plus enzyme showed a more favorable effect on selectivity than free peltatin when a quantitative comparison was made between the tumor growth inhibition and the damage to the blood picture.

Animals↗

Selective tumor DNA synthesis inhibition: in vivo prodrug activation by an exogenous enzyme.

Using the combination of alpha-L-arabinofuranosidase from Aspergillus niger with beta-peltatin A-alpha-L-arabinofuranoside, the selective effect of a new cancer of chemotherapy method based on a pH-dependent activation of cancerostatic prodrugs by exogenous enzymes was studied. In comparative experiments the selectivity of prodrug activation was measured by 3H-thymidine incorporation in tumor and normal tissues of CBA mice inoculated im with the transplantable mammary carcinoma, MA-21224. The results show that this special type of carrier principle may lead to a higher degree of selectivity than the usual direct application of cancerostatic drugs.

Animals↗